Substrates such as metals, glass, plastics, potteries and the like are used as general-purpose substrates for automotive parts, household items, home electric appliances and OA apparatus. The surfaces of these substrates are liable to get stained by the adhesion of waterdrops and water stain due to rain and the like, suspending dust particles, oily matters such as tar of cigarette, fingerprints and sebum of the human hand and the like, and therefore required to have such antifouling functions as to be resistant to these stains and easily remove stains that have once adhered thereto.
In order to exhibit these antifouling functions, a variety of methods have hitherto been proposed. In Patent Publication 1, there is disclosed an antifouling agent composition consisting of a compound having a perfluoroalkylether group. In Patent Publication 2, there is disclosed a glass subjected to a water repellency-imparting treatment and excellent in water repellency, antifouling property and durability, where a treatment film that contains as the primary component an alkoxysilane compound having a perfluoropolyether group is formed on a surface of a substrate. Patent Publication 3 sets forth: a fluorine-containing polymer having a good antifouling property against oily pollutants and particularly having a good antifouling property against fingerprints; and an antifouling substrate on which surface a layer of the polymer is formed. In Patent Publication 4, there are disclosed a silane denatured with a perfluoropolyether group having an excellent in durability, antifouling property imparting effect and particularly having an excellent fingerprint-removability imparting effect and a surface treatment agent containing the same as the primary component.